Unless otherwise indicated herein, the materials described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.
Maintaining hydration benefits a person's health and athletic performance. A reduction in total body water of 1% to 2% of body mass may impair cognitive performance and physical performance. Serious health risks, including death, may occur when water loss exceeds 7% of body mass. Hydration may be defined as a process of absorbing and retaining water in biological tissues. To measure hydration, one may monitor total body water turnover (TBWT), which is the difference between the amount of water that may be absorbed into a body and the amount of water that leaves the body.
A majority of fluid loss during exercise may be due to perspiration. In order to measure the amount of fluid loss to perspiration, the “wash down method” may be utilized to measure the TBWT. However, the wash down method fails to provide a real-time measurement of perspiration. Other measurement methods, such as fabric sensors, osmotic sensors, evaporation sensors, and optical sensors, suffer from limitations such as, saturation concerns, inaccuracy, portability concerns, and an inability to measure the rate of sweat in real-time.